POEC 6387 GIS Workshop Project

INDEX:

 
TR00262A.gif (1715 bytes)Project Objective
TR00262A.gif (1715 bytes)Hardware and Software Used
TR00262A.gif (1715 bytes)Data Sources
TR00262A.gif (1715 bytes)Procedures
TR00262A.gif (1715 bytes)Accuracy Issues
TR00262A.gif (1715 bytes)Conclusion
TR00262A.gif (1715 bytes)Finished Product

Project Objective:

 

The project objective was to establish methodologies for creating zoning coverages. I  created zoning coverages in two North Texas cities and overlaid them onto their soil coverage, highway coverage, and landuse coverage. The objective was also to create geographically linked information that real estate developers can use to plan for their projects.

 


Hardware and Software Used:

Pentium 100 and 133 CPU, MS Windows NT version. 4 OS, Windows 95,

ESRI Arc/INFO ver. 7.1.2, ArcView version 3.0a 


Data Sources:

1. City of Mansfield Planning Department - Official Zoning Map 1996 [paper]

2. City of Cedar Hill Planning and Zoning Department - Zoning Map 1998 [digital]

3. Dallas County Central Appraisal District

4. Texas Natural Resources Web Page, Soil Coverage, Land Use Coverage

5. North Texas GIS Consortium Data Files 1994 and 1997 Street centerline vector maps.

 

Procedures:

1. The street centerline file for Dallas and Fort Worth, the Texas landuse coverage, and the Texas Soil Coverage were downloaded from the internet.

2. Paper zoning maps were purchased from the Cities of Mansfield and Cedar Hill, Texas.

3. I took the paper maps to Thomas Reprographics to have them scanned into .tif image files.

4. I took the image file to the UT-Dallas Green lab and loaded them into ArcInfo to georeference the images to the street centerline file and created registered images to manipulate and create a vector file from the images.

5. I used ArcInfo grid to create grid images of the registered zoning images, then I used the Arc command GRIDLINE to transform the grid image to a vector file that I could use in GIS to create zoning coverages. This did not work. The GRIDLINE command would either create too many arcs or too few. The images had too many lines and markings on them for this method to work properly. Therefore, I decided to digitize the Mansfield zoning map and I obtained the Cedar Hill zoning map in digital form.

6. I digitized the Mansfield zoning map using the digitizer in the UT-Dallas Geology department in PC ArcInfo. I digitized all the arcs that outlined the polygons for the zone categories on the map.

7. I then took the digitized file into ArcInfo at the Green Lab and edited the coverage for errors in Arcedit using the ADD and SELECT and DELETE commands.

8. Next, I cleaned the coverage in Arc with the CLEAN command adjusting the dangle and fuzzy tolerance upwards each time to finally get a coverage with all the polygons closed. I went into Arcedit again to check the coverage for any errors during the clean process and edited the coverage again.

9. I built a polygon coverage with the BUILD command in Arc. Then took that file and georeferenced the tics of the coverage with the same tics in the centerline coverage using the TRANSFORM command in Arc. Therefore the new zoning coverage was transform to North Central Texas Stateplane coordinates.

10. I was now able to use this file to clip the Texas soil and landuse covers to create just Mansfield city limit file of land use and soil. I used the CLIP command in Arc to do this. I ran into a problem with the soil coverage in that it is not completed or attributed well so I could not obtain a clipped coverage for Mansfield.

11. I clipped the soil and landuse coverages for Cedar Hill using the city limits of the City90 coverage from the Dallas County Central Appraisal District.

12. I next imported the Mansfield zoning coverage into ArcView 3.0a and converted it to a shape file. I did the same for all the coverages.

13. I attributed the Mansfield zoning database file in ArcView  by creating a new field for zone and then selecting and highlighting each polygon and editing the data field with the zone information from the Mansfield paper map.

14. I finally created views and layouts for all the coverages in ArcView and the final products can be viewed by clicking below on the finished product.  


 

Accuracy Issues

The accuracy is based on the Dallas-Fort Worth Street Centerline file from the GIS Consortium Data. This data was GPS referenced and has an accuracy of 1 meter resolution. The Mansfield paper zoning map was georeferenced to this file but because it was derived from a paper map the zoning file is not this accurate in all places on the map. This is visible with the streets overlaid. The Cedar Hill Zoning Coverage was already georeferenced to this file.


Conclusions

   Mansfield has 22 zoning categories and Cedar Hill has 15 zoning categories. Each city has its own categories and methods for creating the kind of city its residents desire using zoning ordinances. It would be impossible to create a comprehensive zoning coverage that would apply to all cities. Each city has local control over its affairs. Therefore the best we can do is to continue to research zoning maps and transform them to a GIS format so more people can have access to the data and provide for better decisions. I hope that this data will be useful to those in real estate in Mansfield and Cedar Hill.


The Finished Product

Click Here for Mansfield Maps

Click Here for Cedar Hill Maps

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